release/18.x: [Mips] Fix unable to handle inline assembly ends with compat-branch o… (#77291)

lld/test/ELF/mips-pc-relocs.s

@@ -40,11 +40,13 @@ __start:
 #                                         ^-- (0x20020-0x20000)>>2
 # CHECK-NEXT:    20004:       beqc    $5, $6, 0x20020
 #                                             ^-- (0x20020-4-0x20004)>>2
-# CHECK-NEXT:    20008:       beqzc   $9, 0x20020
-#                                         ^-- (0x20020-4-0x20008)>>2
-# CHECK-NEXT:    2000c:       bc      0x20020
-#                                     ^-- (0x20020-4-0x2000c)>>2
-# CHECK-NEXT:    20010:       aluipc  $2, 0
-#                                         ^-- %hi(0x20020-0x20010)
-# CHECK-NEXT:    20014:       addiu   $2, $2, 12
-#                                             ^-- %lo(0x20020-0x20014)
+# CHECK-NEXT:    20008:       nop
+# CHECK-NEXT:    2000c:       beqzc   $9, 0x20020
+#                                         ^-- (0x20020-4-0x2000c)>>2
+# CHECK-NEXT:    20010:       nop
+# CHECK-NEXT:    20014:       bc      0x20020
+#                                     ^-- (0x20020-4-0x200014)>>2
+# CHECK-NEXT:    20018:       aluipc  $2, 0
+#                                         ^-- %hi(0x20020-0x20018)
+# CHECK-NEXT:    2001c:       addiu   $2, $2, 4
+#                                             ^-- %lo(0x20020-0x2001c)

llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

@@ -150,6 +150,7 @@ class MipsAsmParser : public MCTargetAsmParser {
   bool IsLittleEndian;
   bool IsPicEnabled;
   bool IsCpRestoreSet;
+  bool CurForbiddenSlotAttr;
   int CpRestoreOffset;
   unsigned GPReg;
   unsigned CpSaveLocation;
@@ -552,6 +553,7 @@ class MipsAsmParser : public MCTargetAsmParser {
 
     CurrentFn = nullptr;
 
+    CurForbiddenSlotAttr = false;
     IsPicEnabled = getContext().getObjectFileInfo()->isPositionIndependent();
 
     IsCpRestoreSet = false;
@@ -723,6 +725,16 @@ class MipsAsmParser : public MCTargetAsmParser {
     return getSTI().hasFeature(Mips::FeatureGINV);
   }
 
+  bool hasForbiddenSlot(const MCInstrDesc &MCID) const {
+    return !inMicroMipsMode() && (MCID.TSFlags & MipsII::HasForbiddenSlot);
+  }
+
+  bool SafeInForbiddenSlot(const MCInstrDesc &MCID) const {
+    return !(MCID.TSFlags & MipsII::IsCTI);
+  }
+
+  void onEndOfFile() override;
+
   /// Warn if RegIndex is the same as the current AT.
   void warnIfRegIndexIsAT(unsigned RegIndex, SMLoc Loc);
 
@@ -2307,7 +2319,41 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
 
   bool FillDelaySlot =
       MCID.hasDelaySlot() && AssemblerOptions.back()->isReorder();
-  if (FillDelaySlot)
+
+  // Get previous instruction`s forbidden slot attribute and
+  // whether set reorder.
+  bool PrevForbiddenSlotAttr = CurForbiddenSlotAttr;
+
+  // Flag represents we set reorder after nop.
+  bool SetReorderAfterNop = false;
+
+  // If previous instruction has forbidden slot and .set reorder
+  // is active and current instruction is CTI.
+  // Then emit a NOP after it.
+  if (PrevForbiddenSlotAttr && !SafeInForbiddenSlot(MCID)) {
+    TOut.emitEmptyDelaySlot(false, IDLoc, STI);
+    // When 'FillDelaySlot' is true, the existing logic will add
+    // noreorder before instruction and reorder after it. So there
+    // need exclude this case avoiding two '.set reorder'.
+    // The format of the first case is:
+    // .set noreorder
+    // bnezc
+    // nop
+    // .set reorder
+    if (AssemblerOptions.back()->isReorder() && !FillDelaySlot) {
+      SetReorderAfterNop = true;
+      TOut.emitDirectiveSetReorder();
+    }
+  }
+
+  // Save current instruction`s forbidden slot and whether set reorder.
+  // This is the judgment condition for whether to add nop.
+  // We would add a couple of '.set noreorder' and '.set reorder' to
+  // wrap the current instruction and the next instruction.
+  CurForbiddenSlotAttr =
+      hasForbiddenSlot(MCID) && AssemblerOptions.back()->isReorder();
+
+  if (FillDelaySlot || CurForbiddenSlotAttr)
     TOut.emitDirectiveSetNoReorder();
 
   MacroExpanderResultTy ExpandResult =
@@ -2322,6 +2368,17 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
     return true;
   }
 
+  // When current instruction was not CTI, recover reorder state.
+  // The format of the second case is:
+  // .set noreoder
+  // bnezc
+  // add
+  // .set reorder
+  if (PrevForbiddenSlotAttr && !SetReorderAfterNop && !FillDelaySlot &&
+      AssemblerOptions.back()->isReorder()) {
+    TOut.emitDirectiveSetReorder();
+  }
+
   // We know we emitted an instruction on the MER_NotAMacro or MER_Success path.
   // If we're in microMIPS mode then we must also set EF_MIPS_MICROMIPS.
   if (inMicroMipsMode()) {
@@ -2331,6 +2388,14 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
 
   // If this instruction has a delay slot and .set reorder is active,
   // emit a NOP after it.
+  // The format of the third case is:
+  // .set noreorder
+  // bnezc
+  // nop
+  // .set noreorder
+  // j
+  // nop
+  // .set reorder
   if (FillDelaySlot) {
     TOut.emitEmptyDelaySlot(hasShortDelaySlot(Inst), IDLoc, STI);
     TOut.emitDirectiveSetReorder();
@@ -2356,6 +2421,17 @@ bool MipsAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,
   return false;
 }
 
+void MipsAsmParser::onEndOfFile() {
+  MipsTargetStreamer &TOut = getTargetStreamer();
+  SMLoc IDLoc = SMLoc();
+  // If has pending forbidden slot, fill nop and recover reorder.
+  if (CurForbiddenSlotAttr) {
+    TOut.emitEmptyDelaySlot(false, IDLoc, STI);
+    if (AssemblerOptions.back()->isReorder())
+      TOut.emitDirectiveSetReorder();
+  }
+}
+
 MipsAsmParser::MacroExpanderResultTy
 MipsAsmParser::tryExpandInstruction(MCInst &Inst, SMLoc IDLoc, MCStreamer &Out,
                                     const MCSubtargetInfo *STI) {

llvm/test/CodeGen/Mips/llvm-ir/forbidden-slot-ir.ll

@@ -0,0 +1,71 @@
+target triple = "mipsisa32r6el-unknown-linux-gnu"
+
+; RUN: llc -filetype=asm %s -o - | FileCheck %s --check-prefix=MIPSELR6
+; Function Attrs: noinline nounwind optnone uwtable
+define i1 @foo0() nounwind {
+; MIPSELR6:      bnezc	$1, $BB0_2
+; MIPSELR6-NEXT: nop
+; MIPSELR6:      jr	$ra
+entry:
+  %0 = icmp eq i32 0, 1
+  br i1 %0, label %2, label %3
+  ret i1 %0
+2:                                                
+  ret i1 %0
+3:                                                
+  ret i1 %0
+}
+
+define i32 @foo1() nounwind {
+; MIPSELR6:      addiu	$2, $2, 1
+; MIPSELR6-NEXT: .set	noreorder
+; MIPSELR6-NEXT: beqzc	$2, $tmp0
+; MIPSELR6-NEXT: nop
+; MIPSELR6-NEXT: .set	reorder
+; MIPSELR6:      jrc	$ra
+entry:
+  %0 = tail call i32 asm "1: addiu $0, $0, 1; beqzc $0, 1b", "=r"() nounwind
+  ret i32 %0
+}
+
+define i32 @foo2() nounwind {
+; MIPSELR6:      .set	push
+; MIPSELR6-NEXT: .set	at
+; MIPSELR6-NEXT: .set	macro
+; MIPSELR6-NEXT: .set	reorder
+; MIPSELR6:      .set	noreorder
+; MIPSELR6-NEXT: beqzc	$9, End
+; MIPSELR6-NEXT: nop
+; MIPSELR6-NEXT: .set	reorder
+; MIPSELR6:      addiu	$9, $9, 1
+entry:
+  %0 = tail call i32 asm "beqzc $$t1, End", "=r"() nounwind
+  %1 = tail call i32 asm "addiu $$t1, $$t1, 1", "=r"() nounwind
+  %2 = add nsw i32 %1, %0
+  ret i32 %2
+}
+
+define i32 @foo3() nounwind {
+; MIPSELR6:      addiu	$2, $2, 1
+; MIPSELR6-NEXT: .set	noreorder
+; MIPSELR6-NEXT: beqzc	$2, $tmp1
+; MIPSELR6-NEXT: nop
+; MIPSELR6-NEXT: .set	noreorder
+; MIPSELR6-NEXT: j	End
+; MIPSELR6-NEXT: nop
+; MIPSELR6-NEXT: .set	reorder
+entry:
+  %0 = tail call i32 asm "1: addiu $0, $0, 1; beqzc $0, 1b; j End", "=r"() nounwind
+  ret i32 %0
+}
+
+define i32 @foo4() nounwind {
+; MIPSELR6:      addiu	$2, $2, 1
+; MIPSELR6-NEXT: .set	noreorder
+; MIPSELR6-NEXT: beqzc  $2, $tmp2
+; MIPSELR6-NEXT: addiu	$2, $2, 1
+; MIPSELR6-NEXT: .set	reorder
+entry:
+  %0 = tail call i32 asm "1: addiu $0, $0, 1; beqzc $0, 1b; addiu $0, $0, 1", "=r"() nounwind
+  ret i32 %0
+}

llvm/test/MC/Mips/forbidden-slot.s

@@ -0,0 +1,18 @@
+# RUN: llvm-mc -assemble -mcpu=mips64r6 -arch=mips64el -filetype=obj %s -o tmp.o
+# RUN: llvm-objdump -d tmp.o | FileCheck %s --check-prefix=MIPSELR6
+
+# MIPSELR6:      0000000000000000 <aaa>:
+# MIPSELR6-NEXT: beqzc	$13, 0x0 <aaa>
+# MIPSELR6-NEXT: b	0x0 <aaa>
+# MIPSELR6:      0000000000000008 <bbb>:
+# MIPSELR6-NEXT: beqzc	$13, 0x8 <bbb>
+# MIPSELR6-NEXT: nop    <aaa>
+# MIPSELR6:      b	0x8 <bbb>
+	.set noreorder
+aaa:
+	beqzc $t1, aaa
+	b aaa
+	.set reorder
+bbb:
+	beqzc $t1, bbb
+	b bbb

llvm/test/MC/Mips/mips32r6/relocations.s

@@ -52,17 +52,17 @@
 # CHECK-ELF: Relocations [
 # CHECK-ELF:     0x0 R_MIPS_PC19_S2 bar
 # CHECK-ELF:     0x4 R_MIPS_PC16 bar
-# CHECK-ELF:     0x8 R_MIPS_PC16 bar
-# CHECK-ELF:     0xC R_MIPS_PC21_S2 bar
-# CHECK-ELF:     0x10 R_MIPS_PC21_S2 bar
-# CHECK-ELF:     0x14 R_MIPS_PC26_S2 bar
-# CHECK-ELF:     0x18 R_MIPS_PC26_S2 bar
-# CHECK-ELF:     0x1C R_MIPS_PCHI16 bar
-# CHECK-ELF:     0x20 R_MIPS_PCLO16 bar
-# CHECK-ELF:     0x24 R_MIPS_PC19_S2 bar
-# CHECK-ELF:     0x28 R_MIPS_PC19_S2 bar
-# CHECK-ELF:     0x2C R_MIPS_LO16 bar
-# CHECK-ELF:     0x30 R_MIPS_LO16 bar
+# CHECK-ELF:     0xC R_MIPS_PC16 bar
+# CHECK-ELF:     0x14 R_MIPS_PC21_S2 bar
+# CHECK-ELF:     0x1C R_MIPS_PC21_S2 bar
+# CHECK-ELF:     0x24 R_MIPS_PC26_S2 bar
+# CHECK-ELF:     0x28 R_MIPS_PC26_S2 bar
+# CHECK-ELF:     0x2C R_MIPS_PCHI16 bar
+# CHECK-ELF:     0x30 R_MIPS_PCLO16 bar
+# CHECK-ELF:     0x34 R_MIPS_PC19_S2 bar
+# CHECK-ELF:     0x38 R_MIPS_PC19_S2 bar
+# CHECK-ELF:     0x3C R_MIPS_LO16 bar
+# CHECK-ELF:     0x40 R_MIPS_LO16 bar
 # CHECK-ELF: ]
 
   addiupc   $2,bar

llvm/test/MC/Mips/mips64r6/relocations.s

@@ -59,19 +59,19 @@
 # CHECK-ELF: Relocations [
 # CHECK-ELF:     0x0 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
 # CHECK-ELF:     0x4 R_MIPS_PC16/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
-# CHECK-ELF:     0x8 R_MIPS_PC16/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
-# CHECK-ELF:     0xC R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
-# CHECK-ELF:     0x10 R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
-# CHECK-ELF:     0x14 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
-# CHECK-ELF:     0x18 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
-# CHECK-ELF:     0x1C R_MIPS_PCHI16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x20 R_MIPS_PCLO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x24 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x28 R_MIPS_PC18_S3/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x2C R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x30 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x34 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
-# CHECK-ELF:     0x38 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0xC R_MIPS_PC16/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
+# CHECK-ELF:     0x14 R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
+# CHECK-ELF:     0x1C R_MIPS_PC21_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
+# CHECK-ELF:     0x24 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
+# CHECK-ELF:     0x28 R_MIPS_PC26_S2/R_MIPS_NONE/R_MIPS_NONE bar 0xFFFFFFFFFFFFFFFC
+# CHECK-ELF:     0x2C R_MIPS_PCHI16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x30 R_MIPS_PCLO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x34 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x38 R_MIPS_PC18_S3/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x3C R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x40 R_MIPS_PC19_S2/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x44 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
+# CHECK-ELF:     0x48 R_MIPS_LO16/R_MIPS_NONE/R_MIPS_NONE bar 0x0
 # CHECK-ELF: ]
 
   addiupc   $2,bar

llvm/test/MC/Mips/relocation.s

@@ -237,7 +237,7 @@ baz:    .long foo                          // RELOC: R_MIPS_32 foo
                                            // ENCLE: addiu $2, $3, %tprel_lo(foo) # encoding: [A,A,0x62,0x24]
                                            // FIXUP: # fixup A - offset: 0, value: %tprel_lo(foo), kind: fixup_Mips_TPREL_LO
 
-// DATA-NEXT:  00C0: D85FFFFF CBFFFFFF EC580000 EC480000
+// DATA-NEXT:  00C0: D85FFFFF 00000000 CBFFFFFF EC580000
                                            // ?????: R_MIPS_GLOB_DAT foo
         .set mips32r6
         beqzc $2, foo                      // RELOC: R_MIPS_PC21_S2 foo
@@ -262,7 +262,7 @@ baz:    .long foo                          // RELOC: R_MIPS_32 foo
                                            // ENCLE: lwpc $2, foo # encoding: [A,A,0b01001AAA,0xec]
                                            // FIXUP: # fixup A - offset: 0, value: foo, kind: fixup_MIPS_PC19_S2
 
-// DATA-NEXT:  00D0: 24620000 24620000 00000000
+// DATA-NEXT:  00D0: EC480000 24620000 24620000 00000000
         addiu $2, $3, %pcrel_hi(foo)       // RELOC: R_MIPS_PCHI16 foo
                                            // ENCBE: addiu $2, $3, %pcrel_hi(foo) # encoding: [0x24,0x62,A,A]
                                            // ENCLE: addiu $2, $3, %pcrel_hi(foo) # encoding: [A,A,0x62,0x24]